Invar scale, no.4328 a little over a metre long, divided to 1mm and also to 0.01 ft., Rectangular in section, 2.45mm by .54mm. with N.P.L. Certificate dated 30th December, 1908 Invar scale
Invar rod no. 8858, 45-inches long and 8 mm diameter, with N.P.L. certificate dated 7th May 1912 (mean coefficient of linear dilatation between the temperatures 0.6°C and 30°C is 0.0000000 per 1°C). Invar Rod, 1900-1912
